If you care more about the dollar than Amazon:
https://www.mathsisfun.com/puzzles/where-did-the-dollar-go--...
>When the Waiter returns 3 dollars, the 3 friends had paid $25 to the Cashier and $2 to the Waiter. $25+$2 = $27 = 3 x $9.
https://www.mathsisfun.com/puzzles/where-did-the-dollar-go--...
>When the Waiter returns 3 dollars, the 3 friends had paid $25 to the Cashier and $2 to the Waiter. $25+$2 = $27 = 3 x $9.
> Three tourists stop at a hotel, and the manager tells them that a shared room will cost $30. Finding the price agreeable, they pony up $10 each and retire to the room. Later that afternoon, the manager, who is honest, realizes that the room was meant to be priced at $0. The manager orders the bellhop to return the excess $30 to their guests. The bellhop, who is not honest, takes $30 from the register and return only $1 to each tourist, pocketing the remaining $27.
> Now, each of the three tourists has spent $9, for a total of $27. The bellhop has retained $27, which brings the total to $54. Where did the other dollar go?
The customers collectively are at -10*3 + 1*3 = -$27. The hotel is at 10*3 - 5 = $25 The bellhop is at 5 - 1*3 = $2
And those sum to zero for the system; no money was created or destroyed.
Or, thinking in terms of physical bills, the bellhop's two dollars are a subset of the 27 the customers paid out and adding them is double-counting. The real math behind the problem is just 27 = 25 + 2.
Customers: 0 -30 -30 -27
Hotel : 0 30 25 25
Bellhop : 0 0 5 2
Total : 0 0 0 0Now, each of the three tourists has spent $8, for a total of $24. The bellhop has spent $1, which brings the total to $25. Where did the other 5 dollars go?"
"The bellhop, who is very much not honest, takes $10 from the register and return only $1 to each tourist, pocketing the remaining $7— the guests don’t have to fuss over uneven change that way.
Now, each of the three tourists has spent $9, for a total of $27. The bellhop has retained $7, which brings the total to $34. Where did those other 4 dollars come from?"
The room is $25. Everyone paid $25 for the room + a $2 "tip" to the bellhop.
That said, I'm going to have fun emailing it to my parents. ;)
1. A three-headed tourist gives $30 to the hotel.
2. The bellhop takes $5 from the hotel.
3. The bellhop gives $3 to the tourist.
Now it's clear that the tourists are down $27, the hotel is up $25, and the bellhop is up $2.